1. Field of the Invention
This invention relates to a process of smoothing a coated-layer formed on a support and the apparatus for use in such process and, for example, to a process suitable for smoothing a magnetic coated-layer of a magnetic recording medium immediately after it is coated, and the apparatus for use in such process.
2. Description of the Prior Art
Heretofore, in the manufacture of magnetic recording media and the like, there have been proposed the process for smoothing surfaces in which a continuously travelling flexible support is coated with a coating liquid in a variety of coating processes and the surface of the coated-layer is smoothed in one of the various smoothing processes while the coated-layer still remains wet (normally, immediately after coating).
There are well known processes including, for example, such a process using a flexible sheet as disclosed in Japanese Patent Publication Open to Public Inspection (hereinafter called Japanese Patent O.P.I. Publication) No. 22835/1975; such a process using a bar shaped stiff member having a smooth surface called a smoothing bar or such a process using a deformable plate-shaped stiff member having a smooth surface called a smoothing blade as disclosed in Japanese Patent 0.P.I. Publication No. 8646/1979; and further such a process using a combination of the described flexible sheet and a bar as disclosed in Japanese Utility Model 0.P.I. Publication No. 6008/1980. In any one of these processes, however, the effect of smoothing a coated-layer is not satisfactory. For example, it is difficult to prevent a longitudinal streak caused in the travelling direction of a support, i.e., an irregular thickness in the width direction of a support, when a magnetic paint is coated on the support; and it is also difficult to prevent such fine streaks like the fine grains of a lauan lumber which are caused by a supply of the coating liquid with the supply thereof being reduced closely to an amount required to coat on. Resultantly, these difficulties will bring about such a deterioration of the characteristics of a magnetic recording medium as a lowering of the electromagnetic output, an increase in the drop-out and the like. It may be able to estimate that these troubles may be caused by well known smoothing processes in which a coated-layer is smoothed only in the travelling direction of a support.
The abovementioned Japanese Utility Model 0.P.I. Publication No. 6008/1980 discloses that a bar provided with a flexible sheet is reciprocated in the direction perpendicularly intersecting to the travelling direction of a support. It may be presumable, by and large, to obtain an effect that a longitudinal streak on a coated-layer may be dispersed in the width direction and then eliminated thereby. To be more concrete, a flexible sheet for smoothing the surface of the coated-layer is reciprocated in its entirety and thereby the components of a coating liquid are moved forcibly in the width direction and are then smoothed, at the same time and under the same conditions, by the pressure of the sheet. In this process, however, the film-like sheet is still reciprocated constantly. It is, therefore difficult to smooth the surface of the coated-layer without fail. In other words, the components of a coating liquid are being held constantly moved in the width direction of a support by the reciprocation movement of a sheet and at the same time the moving coating liquid is separated from the sheet, therefore, all the reciprocation stress cannot forcibly be eliminated and the remaining stress is kept in the coating liquid. Resultantly, the remaining stress will cause an irregular thickness of the coated-layer. Streaks are also caused by a wrinkled sheet. In addition, a complicated driving mechanism must be provided for vibrating the entire flexible sheet and such vibrations are transmitted to a coating device, so that there may be some instances where a coating failure may be brought about. Further, because of using a sheet-shaped smoothing means, there may be troublesome in handling and installing the means, and still further air may be dragged between a sheet and a coated-layer when processing at a high speed, so that there may be a fear of coating in irregular thickness.